Attachment plug



Oct. 12, 1937. G. G. HIGGINS 2,095,439

\ ATTACHMENT PLUG Filed Jupe 21, 1954 Patented Oct. 12; 1937 feri-'r'lalsl'r OFFICE ATTACHMENT PLUG Grver B. Higgins, chicago, 111. l jApplicatien Juneau 193fr`seria1Na7319 j tachment4 plugs; and more particularlyV to such plugs which. are adaptedier; use in connection with electricirons,` electric cooking devicesfand A' f. n various :household appliances.V

,'fIngthe use of plugs-of this character it is found that `considerable. heat 1 is generated within', the plug,due generally tothe looseness of the connections between the stationary terminals and .the terminals ofthe plug,.or due to similar looseness `.in 1thecontacts of the switch mechanism whichds-provided inV many plugs of this type. As :a result the exterior surfaceof the plug attains 'amelatively high temperature `so `that it is dini- :cult -'Or ,the V.user Vto handle and manipulate the plug; Such heatwithin theplug body also causes undue :deterioration of the terminals and the switch mechanism.. A, Y f

With this situation in mind, an important ob- 29 iectzof .the invention is `to provide a plug :of this character wherein high Ainterior and exterior temperatures are avoided'so .as to-facilitate han- .dling `of :the plug .and increase the life of the mechanismihoused .in ,the vplug body.

Anotheriobjectlof.the-invention is to provide aV plug. wherein arelatively inexpensive molded inasnlatingzhousing and a reinforcing and protecting fmetallic .armorarelso-constructed and arranged that objectionable highltemperatures of the ,plug

,23p arefavoided.. i. 1- A,

lOther .objects .and advantages willbecome ap.-

- parent V.from.1the :following description. ,taken .in Y

connection l'with .the accompanying drawingin Which, Y Y x35 Rigi isza perspective View. of an ,armored at- -gtachment ,plug lembodying :the features `of the invention, the plug being of the type which has switch mechanism housed therein. I

Eig. .21-isanxelevational View ofthe plug of Fig. V1 with one. section, .ot-.the housing and Varmor rennoved ato fshow the switch. `and the terminals amounted withinfithe other section of the housing.

Eligifa:islaftransverse'sectional 4view taken along Y A5.rig lPilsfaiview'similare-tc Fig. 3 showing an 'nlternativeform of. construction.

' 1"ig.5V is :an elevational viewof another :form of :plug.embodying"thelinvention-` Fig. 6 -is a transverse-'sectional view taken along `:1tl'le`lineIS-"B of Fig. =5. Y v Y `.Fig-'57 'is a viewsshowi'ngan alternative form .of splug'embodying thezinvention. l Y

.Fig. :8 illustrates,V in elevation, another Valternative form of ,the invention.V 1

.155 Figs. Snandglopare `fragmental sectional views channels.

g Vi C1ainis. (01;200-51) "The invention relatesjgenerally to electrical attaken along the line 9 9 of Fig. 8 and showing two methods of forming the heat conducting While I have shown in the accompanying drawing andY will herein describe in detail the preferredembodiment of the invention together with several alternative embodiments thereof, it is to berunderstood` that this disclosure is given for the purpose ofillustrating the invention and 'is not intended as a limitation of the invention to 10 the construction disclosed. In the Vappended claims, I am to 4cover all jmodications and a1- ternative constructions falling within theV scope of the invention.

In Vthe form illustrated `in Figs..1 to- 3 of the 15 Adrawing the invention is embodied in a switch type attachment plug having` a separable tWopart casing or .housing I0 composed of sections II and I2 of molded insulating material, and within which friction terminals I3 and a switch 20 Y mechanism I4 are mounted. About a substantial portion of the housinglll a two-part reinforcing and protecting armor 'I5 is providedto prevent injury to the relatively brittle housing I0 in case the-plug is dropped or subjected to other unusual 25 impact.` Bolts I6 extending through suitable apertures `(not shown) inthe armor and throughVV bores II. (Fig. 2) molded in the sections II and I2 serve to hold the sections of the armor I5 as Well as the housing sections II and I2 in assem- 30 bled relation.

`As shown in Figs. 2 and 3 the housing sections Il and I2 are recessed to form a switch chamber '20 adjacent the upper end of the plug and spaced parallel channels 2IV extending longitudinally of l35 the plug and opening through the lower end thereof to receive the spring Aterminals I3. At its upper end'the housing provides an opening 209' through which 'a'l cord'22V may extend for connection of its wires V23 to screw terminals 24,`the 40 terminals 24 being mounted on4 the section I I adjacent the upper limit of the switch chamber 2U.

A conductor strip 225 connects one terminal 24 f'with one of the spring terminals I3, while springY fstrips .26` and 21 extend .toward eachother .from 45 the-other terminals I'3 and-,24 to form the spaced.Y

`stationary contacts of the-switch mechanismy I4.

A switch arm `28, pivoted on vthe sectionlZ and actuated by a pivoted operating lever 29 in conjunction with a compression spring 30 ina con- 50 .ventional manner, is shiftedlwith a conventional .snap-action to and from lits closed position where- 1in;thearm 28 bridges the contacts formed by the 'spring strips 26 and 21. lever `253 extends from the housing through a slot The switch operating sections 3l in one side wall 32 of the switch chamber 20.

As an incident to the transmission of electricity through the switch mechanism I4 and the spring terminals I3 considerable heat is ordinarily generated so that the temperature of the plug as a whole gradually rises during continued use of the plug. This high temperature is objectionable in all types of plugs, but is particularly so when the armor I5 is employed, since the metal of the armor retains the heat and makes it difficult to handle and manipulate the plug. It also causes undue deterioration of the terminals I3 and switch I4 and produces a sticking tendency in the switch.

The present plug, however, is constructed so as to avoid such a building up of high temperatures, with the result that use of the armor I5 is rendered practical. The armor I5, in turn, by its action in reinforcing and protecting the cast housing sections II and I2, makes it possible to form these sections from a moldable insulating substance which is less expensive than the material which must be used in an unarmored plug.

To avoid the building up of high temperatures in the plug, the sections I I and I2 and the armor sections I5 are so formed as to provide for a continuous circulation of air through the hollow interior of the plug, whereby to dissipate and carry or the heat as it is generated. Thus a plurality of openings 35, 36 and 31 are formed in the various housing and armor sections through which cooling currents of air may pass continuously as indicated by the arrows in the various figures of the drawing.

The openings are, in the present instance, formed in the top wall of the switch chamber 2D to permit upward travel of the air which is heated by the warm elements of the switch mechanism I4. The opening 36 also communicates with the switch chamber 2l and is formed in the side wall 32a of the switch chamber opposite the wall 32.

Cooling of the spring contacts I3 and of the lower portions of the housing sections II and- I2 is obtained by locating the opening 31 in space between the two channels 2I in which the terminals I3 are housed. As shown in Figs. 2 and 3, the opening 31 preferably takes the form of an Velongated slot positioned longitudinally of the plug and extending entirely through the sections II and I2 and the two sections of the armor I5. Flanges or ledges 38 formed on the sections II .and I2'dene the opening 31 and the inner sides of the channels 2l, and in the preferred form illustrated in Fig. 3 of the drawing, the ledges 38, throughout the length of the slot 31, terminate .short of each other so as to define passages 39 opening laterally from the slot 31 into the channels 2|. Thus the air which is heated within the channels 2| may move from the channels 2I through the passages 39 and outwardly through the slot 31 as indicated by the arrows in Fig. 3.

The direction of movement of the air currents may vary, of course, in accordance with changes in the relative temperatures of the various parts of the plug assembly, or in accordance with the position of the plug when in` use, vbut it will be noted that circulatory paths are provided which permit a cooling air circulation under all conditions.

In Figs. 2 and 3 it will be clear that the armor I5 are formed to give the maximum strengthening and protecting effect. Thus it will be seen that the side edges of the sections I5 are proportioned so as to be in firm abutment with each other in their assembled relation, while inturned flanges 40 and 4I are formed about the opening 31 and the lower edge respectively to protect the adjacent edges of the housing and properly distribute any shock to which the armor may be subjected.

The embodiment illustrated in Fig. 4 of the drawing is in most respects similar to that of Fig. 4, but is provided with ledges 38a on the sections II and I2 which extend toward. each other into abutment so that the slot 31 is in the form of a closed passage entirely through the plug body. In this form the cooling eiect is obtained by contact of the air with the inner surfaces of the ledges 38a.

In Figs. 5 and 6 of the drawing the invention is embodied in an unarmored attachment plug which is of a smaller size than the form shown in Fig. l due to the fact that the switch mechanism has been omitted. This plug has a housing formed from molded insulating material in two separable sections 46 and 41 which are held together by bolts 48 extending through suitable apertures in the sections. In the lower end of the housing 45 spaced parallel channels 49 are formed to house spring terminals 59, and the heat generated about these terminals is dissipated by the provision of a Ventilating slot 5I formed between the channels 49 and extending entirely through the plug housing 45. The slot 5I is defined in a measure by ledges 52 which terminate short of each other so as to provide openings 53 through which heated air may pass from the channels 49 into the slot 5I as indicated by the arrows in Fig. 6. 'I'hus a continuous circulation of cooling air prevents the building up of high temperatures in the plug housing.

Fig. '7 of the drawing illustrates a plug having a sectional body similar to the form shown in Figs. l to 3, but embodying a conventional switch mechanism (not shown) arranged for actuation by a reciprocable transverse slide bar 63 which projects at its opposite ends through sliding bearings 64 (only one shown) formed in the body 66. In this form the upper portion of the plug body which houses the switch mechanism is cooled through the provision means whereby the air heated within the plug may escape from the interior of the plug.

This means as herein shown comprises a single relatively large Ventilating opening 65 formed in the upper portion of the plug body 60, from which the heated air may pass as indicated by the arrows in Fig. 7. Additional openings may, of course, be provided as determined by the heat generating characteristics of any particular plug design.

Figs. 8 to 10 illustrate an embodiment of the invention wherein the Ventilating opening or openings in the plug body 66 are covered or pro- S30 tected so as to avoid .all question as to danger due to accessibility of the conductors within the plug body. Thus the body has a transversepassage or opening 61 similar to the passage 38a' of Fig. 4 or passage 31 of Fig.v 3, and as protecting means to prevent insertion of a conductor into the opening, a guard or sheath is arranged in overlying relation to the opening 61 in such a manner as to permit lateral escape of the heated air between the body 66 and the sheath. This'l vide for the escape of the heated air one or more "715 passages 69 may be formed by appropriate shaping of the body 66, the armor 68, or both, to extend from the opening 61 to the edge of the .armor 68. 'Ihese passages 69 preferably extend" continuous cooling action in the attachment plug of the body, terminals mounted in said channels which prevents undue heating of the plug and renders the same more reafdily usable. AThis cooling action also prevents damage to the various metallic parts of the device.

Due to the cooling of the plug, the use of a protective armoris rendered feasible, with the result that the insulating housing may be manufactured from less expensive material, and hence the plug as a whole may be more economically manufactured.

I claim as my invention:

1. An vattachment plug comprising an insulating body having a pair of laterally spaced channels formed therein opening through one end with the major portion of the outer surfaces of said terminals spaced from the walls of saidV channels, said body having a passage therethrough located between said channels and transversely related thereto, and said body also being formed to provide openings from said channels into said passage.

2. A` plug of the character described comprising,'in combination, a hollow insulating body, terminals inV said body, openings in said body through which cooling currents of air may move into and out of said hollow body, a metallic armor surrounding and protecting a portion of said body, said armor being formed in aV plurality of sections and having openings therein registering with certain of said openings in the body, said openings in the armor sections having inturned marginal flanges extending into the corresponding body openings in iirm engagement with the sides thereof, and means clamping said armor sections in position.

3. An attachment plug comprising a hollow insulating body having an open end, a pair of Vterminals mounted therein adjacent said end,

said body having a plurality of openings therein throughY which cooling air may circulate into and Vout of said hollow body, reinforcing and protecting means for said body comprising two armor sections 'adapted to embrace a substantial portion of said body, said armor sections being formed so that its edges abut each other when the armor is in rm engagement with the outer 'surface of said body, inturned flanges on the armor sections protecting the end edges ofV said body at said end thereof, said armor having openings therein registering with certain of said openings in said body, inturned flanges on said armor about said openings in the armor to extend into the Ycorresponding openings in the body, and means for holding the armor sections in position on said body. Y Y

4. An attachment plug comprising in combination, a hollow insulating body providing a switch chamber in its upper end and a pair of laterally spaced longitudinal channels adjacent to and opening endwise through the lower end of said body, terminals in said channels, switch mechanism in said switch chamber electrically connected to said terminals, said body having a plurality of openings therein through which cooling air may circulate into and out of said switch chamber to cool said switch, and said body also having an openingin its lower side portion through which heated air may pass from said channels. Y GROVER B. HIGGINS. 

